One inflammatory molecule in particular, LTB4, is released by immune cells living in extra fat, called macrophages. Positive feedback then signals for the body to release more macrophages, which then release more LTB4 into the fatty cells in the liver, researchers found.

"This study is important because it reveals a root cause of type 2 diabetes," the study's senior author Dr. Jerrold M. Olefsky, professor of medicine and associate dean for scientific affairs, said in a statement. "And now that we understand that LTB4 is the inflammatory factor causing insulin resistance, we can inhibit it to break the link between obesity and diabetes."

The research was funded in part by the National Institute of Diabetes and Digestive and Kidney Disease, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and Merck Inc.